In the manufacture of semiconductor devices or flat plate displays, various substrate processing apparatuses (thin film formation apparatuses for forming prespecified thin films on the processed substrate, impurity addition apparatuses for conducting the addition or impurities such as boron, phosphorous, arsenic, and the like) are employed; however, a composition in which all processing apparatuses are built into a single chamber is rare, and it is generally the case that the processing apparatuses are compartmentalized through the medium of a conveyance path under atmospheric pressure or a conveyance passage (tunnel chamber), or via opening and closing mechanisms, from other processing chambers.
However, since the instances of various types of handling of the processed substrates, such as gripping, moving, and the like, are frequent, and particularly since the implements and the like which come into contact with the processed substrate at the time of such handling are normally formed using fluorine resin or silica insulating film or the like in order to avoid metallic contamination of or damage to the processed substrates, the processed substrate is positively (in some cases, negatively) charged as a result of the electrification rank relationship thereof with respect to the implements at the time of contact, and the potential of these processed substrates easily becomes high.
In addition, In order to prevent the depositting of dust on the processed substrate, a gas flow which bas been passed through a filter is normally caused to flow in the vicinity of the processed substrate, and because floating particles, water, and trace amounts of gaseous impurities and the like, even if in very small amounts, are contained in this gas flow, dust is actively deposited on the charged processed substrate, or the interior of the processing apparatus is contaminated. Furthermore, with respect to the conveyance of the processed substrate between apparatuses, the processed substrate is commonly first transferred to a pretreatment chamber and placed on a prespecified installation platform, and is then transferred to a reaction chamber.
In this case, during the transfer of the processed substrates, instances in which the gripping, rubbing, or the like of the processed substrates by means of the handling mechanisms are frequent, and furthermore, the implements comprising the handling mechanisms are normally formed using fluorine resins, silica, or the like in order to avoid metallic contamination of the processed substrates, so that as a result of the electrification rank relationship of the processed substrate with respect to the implements, the processed substrate is positively charged, and easily attains a high potential.
The following methods are commonly known for the prevention of the charging of processed substrates and processed substrate carriers, that is to say, as charge removal mechanisms; first, a method employing an ionizer, that is to say, a method in which corona discharge is generated in an ambient atmosphere in which a processed substrate or a processed substrate carrier is placed, and by means of this, the generated ions and the charges are neutralized,
secondly, a method in which the processed substrate is subjected to handling by means of a resin material in which a grounded metallic body or a grounded conductive substance (carbon, metal, or the like) is included, and charges are thus neutralized, and the like.
However, in the first conventional method above, corona discharge in an ambient atmosphere Is employed, so that the generation of electromagnetic noise as a result of this discharge causes electrical disturbance of instruments around the processing apparatus, and the remaining potential of the processed substrate becomes high, so that this is insufficient as a charge removal apparatus. Furthermore, among the ions which are generated, the positive ions are mainly the water ions (H.sub.2 O).sub.n H.sup.+, and these water ions (H.sub.2 O).sub.n H.sup.+ contribute to the growth of a natural oxide film on, for example, the surface of a semiconductor substrate, while the negative ions are largely CO.sub.3.sup.-, NO.sub.x.sup.-, and SO.sub.x.sup.- ions, and these ions are all strongly oxidizing, and cause the formation of a natural oxide film, in the same manner as the positive ions described above.
On the other hand, in the second conventional method described above, the metal or conductive material is in direct contact with the processed substrate, so that impurities therefrom contaminate the processed substrate, and this causes the generation of dark currents or leak currents.
In processing apparatuses in which a processed substrate is transferred between different atmospheres as described above, even if charged neutralization of the processed substrate is conducted in one atmosphere (for example, in a tunnel chamber), there are cases in which the charging of the processed substrate occurs again as a result of contact with other materials during transfer to another atmosphere (within a pretreatment chamber).
In such cases, there are cases in which it is structurally difficult to conduct charge neutralization by means of the above methods in the latter atmosphere, and furthermore, even if such charge neutralization is conducted, there is a danger that the growth of natural oxide films, operational errors as a result of electromagnetic noise, impurity contamination as a result of conductive substances, the increase in the remaining potential, and the like, will disturb or render impossible the desired processing.
Furthermore, in many processing apparatuses, the atmosphere in the main reaction chamber is of reduced pressure when compared with the ambient air pressure, and accordingly, within pretreatment chambers coupled thereto, it is necessary to establish a reduced pressure which is approximately equivalent to that within the reaction chamber at least prior to the transfer of the processed substrate, and it is necessary to establish a method for the easy removal of charges even in such reduced pressure atmospheres.
The present invention solves the problems present in the conventional technology described above; it has as an object thereof to provide a neutralizing apparatus which is capable, with respect to charged bodies such as processed substrates or processed substrate carriers, to prevent the generation of electromagnetic noise, to completely eliminate remaining potential, to realize an impurity contamination-free state, and to prevent the formation of natural oxide films, the generation of dark currents or leak currents, and emission irregularities in flat plate displays, and which is furthermore capable of conducting the easy neutralization of charges even in the process of transfer between differing atmospheres.